Plant Biology ISSN 1435-8603 RESEARCH PAPER Reproductive ecology of Ocotea catharinensis, an endangered tree species T. Montagna1 , J. Z. Silva1, T. G. Pikart2 & M. S. Reis1 1Nucleo de Pesquisas em Florestas Tropicais, Universidade Federal de Santa Catarina, Florianopolis, Santa Catarina, Brazil 2 Laboratorio de Entomologia, Centro de Ciencias^ Biologicas e da Natureza, Universidade Federal do Acre, Rio Branco, Acre, Brazil Keywords ABSTRACT Conservation; floral biology; mating system; phenology; pollination; seed dispersal. • Ocotea catharinensis (Lauraceae) is an endangered tree species from the Brazilian Correspondence Atlantic Rainforest. Currently, little is known about the reproductive ecology of this T. Montagna, Rodovia Admar Gonzaga, 1346. species. Aiming to propose conservation measures, we described aspects related to Florianopolis, Santa Catarina, Brazil. phenology, floral biology, pollination, seed dispersal and mating system of O. cathari- E-mail: [email protected] nensis. • We conducted phenological observations in 62 individuals for 2 years. In one repro- Editor ductive event, we evaluated nectar production, stigmatic receptivity and pollen viabil- Z.-X. Ren ity. Floral visitors were observed, identified and classified on a scale of pollination effectiveness. Seed dispersers were observed and identified using camera traps. Finally, Received: 19 March 2018; Accepted: 16 May the mating system was evaluated through pollen/ovule ratios, experimental pollination 2018 treatments and genetic analysis with molecular markers. • Ocotea catharinensis presented a supra-annual fruiting pattern with a substantial doi:10.1111/plb.12847 reduction of reproducing individuals from bud phase to ripe fruit phase. Several mechanisms prompting cross-fertilisation were identified, such as attractive, herkoga- mic and protogynic flowers. The main floral visitors and pollinators were from the Diptera order, and all seed dispersers were birds. The species presented a predomi- nantly outcrossed mixed mating system with significant selfing rate (17.3%). • Although based on restricted evidence, we hypothesised that selfing is an escape mech- anism for situations unfavourable to cross-fertilisation. Specifically, for the studied population selfing is a response to reduced population size, which is caused by the non-reproduction of all potentially reproductive individuals and by past exploitation events. Therefore, conservation efforts should be able to enhance population sizes, as well as prevent overexploitation. et al. 2014). Pollination and seed dispersal ecology studies can INTRODUCTION provide valuable information related to gene flow, such as vec- Knowledge of plant reproductive ecology is critical to predict tors, distances and possible limitations (e.g. Dick et al. 2003; population survival ability and to propose viable conservation Danieli-Silva & Varassin 2013). Mating system studies, in turn, efforts in the case of endangered species (Bernardello et al. examine how individuals from a given species cross to form the 2001; Newton 2007). Studies on reproductive ecology are com- progeny. Consequently, it is possible to estimate, for instance, prehensive, often reporting on aspects related to phenology, outcrossing and selfing rates, number of pollen donors and the floral biology, pollination and seed dispersal ecology and mat- degree of inbreeding in the progeny (e.g. Conte et al. 2008; ing system (e.g. Mariot et al. 2014; Custodio et al. 2017). Such Rogalski et al. 2017). data are fundamental to a complete understanding of repro- All these study fields are deeply connected and provide use- ductive processes of a given species, including possible ecologi- ful knowledge to identify possible factors that can reduce the cal relationships with other organisms, such as pollinators or reproductive ability of a given species. Thus, conservation pro- seed dispersers. posals can best be supported when based on reproductive ecol- Phenological studies refer to recurrent (cyclic) events and ogy studies. For instance, one mating system parameter, their timing in plant species (Newstrom et al. 1994). Such stud- effective variance size, is commonly used to determine how ies allow us to know the onset, peak, ending, intensities and many seed trees (or seed plants) are necessary for seed collec- variations between individuals, populations and years of flow- tion in order to retain a given effective size (Hmeljevski et al. ering and fruiting periods of a given species (e.g. Grogan & 2011; Ferreira et al. 2012). Furthermore, pollination vectors Loveless 2013). Floral biology is concerned with flowering can alert researchers to the need for conservation efforts, espe- (Percival 1965), and studies in this field can provide informa- cially for species with few, or even single, pollinators, such as tion about nectar production, stigmatic receptivity, pollen via- figs (Janzen 1979) or Ocotea porosa (Danieli-Silva & Varassin bility and floral morphology (e.g. Kubitzki & Kurz 1984; Pacini 2013). 926 Plant Biology 20 (2018) 926–935 © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands Montagna, da Silva, Pickart & dos Reis Reproductive ecology of Ocotea catharinensis Ocotea catharinensis is a long-lived tree species that occurs in flowering (buds and open flowers; Fig. 3) and the fruiting (un- the Brazilian Atlantic Rainforest. This climax species is dis- ripe and ripe fruits) using binoculars. We applied the method tributed between latitudes 19°570 S (Saiter & Thomaz 2014) proposed by Fournier (1974) to score the intensity of pheno- and 30°150 S (Carvalho 1994). O. catharinensis can reach 30 m logical events, attributing 0 for individuals without phenologi- in height and can surpass 100 cm diameter at breast height cal activity, and 1, 2, 3 and 4 for individuals with 1–25, 26–50, (DBH) when adult (Reitz et al. 1978). It was considered as the 51–75 and 76–100% of phenological intensity, respectively. dominant and most abundant tree in the higher stratum of Phenological index to each phenophase was obtained by sum- Ombrophilous Dense Forest (Veloso & Klein 1959; Klein ming all intensity values (6¼0) and averaging by the number of 1980). In spite this dominance, several aspects O. catharinensis individuals presenting phenological activity during a given reproductive ecology remain poorly understood. For instance, month, modifying the proposal of Bencke & Morellato (2002). the literature contains little, to no, information regarding nec- We compared the average DBH between reproductive and tar production, stigma receptivity, pollen viability and floral non-reproductive individuals through a confidence interval visitors. Furthermore, the mating system was only indirectly (CI) (95%) obtained with 1000 bootstrap replicates. Possible estimated (apparent outcrossing rate; Tarazi et al. 2010), and relationships between phenological events, including monthly only one study focused on phenological aspects of this species frequency of individuals presenting buds, open flowers, unripe (Silva et al. 2000). or ripe fruits and climatological data, including monthly aver- This species was intensively exploited for timber production ages of mean temperature, maximum temperature and mini- (Reitz et al. 1978), and it resulted in severe reductions to popu- mum temperature and total monthly rainfall, were investigated lation sizes in Santa Catarina state (Schorn et al. 2012). Because through Spearman correlation. Climatological data were of the exploitation processes and the high fragmentation of the obtained from an official meteorological station 18 km from Atlantic Rainforest (Ribeiro et al. 2009), O. catharinensis cur- the study area. rently figures on the Brazilian List of Endangered Plant Species (MMA 2014) and also on the IUCN Red List (Varty & Guadag- Floral biology nin 1998), classified as vulnerable. Furthermore, a recent study has shown that O. catharinensis presents low recruitment into Floral biology aspects, such as nectar production, stigmatic the seedling category, potentially harming the population receptivity and pollen viability, were evaluated using three dynamics in the long term (Montagna et al. 2018). metallic towers (11–13 m in height) installed near three indi- The endangered condition of O. catharinensis demands stud- viduals in order to gain access to flowers. Due to the steep ies to better understand aspects of its reproductive ecology. Nev- topography at the study site, we were able to install only three ertheless, comprehensive knowledge gained from reproductive towers. Standing crop nectar was evaluated every 2 h, from ecology, although difficult to achieve, is very relevant for the tar- 05:00 to 23:00 h, in ten different flowers from three individuals get species of our study. Therefore, in order to propose feasible per evaluation using a 1 ll microcapillary tube. In each of these conservation actions, we investigated the following aspects of evaluations, which were conducted over 5 days, the air temper- O. catharinensis: (i) reproductive phenology; (ii) floral biology: ature and the presence or absence of floral scent was also nectar production, stigmatic receptivity and pollen viability; recorded. Nectar soluble solids concentration (24 flowers from (iii) floral visitors and pollinators; (iv) seed dispersers; and three individuals) was measured with a portable refractometer (v) mating system. Some of these aspects are described here for only when the volume of nectar extracted was >0.5 ll needed the first time, such as nectar production,